An Operating Mode of Voltage Source Inverter for Fault Current Limitation

In recent years, various types of fault current limiter (FCL) have been developed, because installation of the FCL will bring a lot of benefits to power system operation. Some power-electronics-based FCLs have been proposed with growing power ratings of converters. It is one of the distinctive features of such FCLs that they can employ some valuable control options in its standby mode. Authors have developed a new type of FCL, which consists of a series reactor and a series-connected voltage source inverter. The inverter compensates a voltage drop across the series reactor and employs some optional controls in a standby mode. But, in case of a system fault, it will be operated in a virtual inductance mode to reduce the fault current. However, the inverter has to handle a large current in the fault current limitation mode. This paper newly proposes that the inverter should be operated in a square-wave mode for fault current limitation in order to reduce the number of switching transitions. In this paper, the operating characteristics of the FCL are confirmed by some simulation studies